# Characterization of the transcriptome, nucleotide sequence polymorphism, and natural selection in the desert adapted mouse Peromyscus eremicus

## TL;DR

This paper studies the genetic adaptations of a desert mouse to survive without drinking water.

## Contribution

The study identifies genes under selection in a desert mouse linked to osmoregulation.

## Key findings

- Transcripts in P. eremicus show evidence of both purifying and balancing selection.
- The gene Slc2a9 is found to be under enhanced selection in desert-adapted mice.
- Transcriptome data was collected from four tissues and multiple individuals.

## Abstract

As a direct result of intense heat and aridity, deserts are thought to be among the most harsh of environments, particularly for their mammalian inhabitants. Given that osmoregulation can be challenging for these animals, with failure resulting in death, strong selection should be observed on genes related to the maintenance of water and solute balance. One such animal, Peromyscus eremicus, is native to the desert regions of the southwest United States and may live its entire life without oral fluid intake. As a first step toward understanding the genetics that underlie this phenotype, we present a characterization of the P. eremicus transcriptome. We assay four tissues (kidney, liver, brain, testes) from a single individual and supplement this with population level renal transcriptome sequencing from 15 additional animals. We identified a set of transcripts undergoing both purifying and balancing selection based on estimates of Tajima’s D. In addition, we used the branch-site test to identify a transcript -Slc2a9, likely related to desert osmoregulation – undergoing enhanced selection in P. eremicus relative to a set of related non-desert rodents.